The present invention relates to a reciprocating piston internal combustion engine having for each cylinder a cylinder head sealing element which is especially in the form of a metal ring, is disposed in a recess provided in a light metal cylinder head, and forms a sealing surface relative to a cylinder sleeve.
Sealing surfaces of light metal cylinder heads, which are connected with a cast-iron cylinder sleeve, due to high surface pressure and radial relative movement of cylinder head and cylinder sleeve as a result of different thermal expansion properties of light metal and cast iron, are subjected to extremely high stresses which can lead to destruction of the sealing surfaces and failure of the cylinder unit.
A cylinder for reciprocating piston internal combustion engines is known (German Patent No. 10 28 386), according to which the sealing surface of the light metal cylinder head is formed by an integrally cast heavy metal ring. Although in this way the radial relative movement at the sealing surface of cylinder head and cylinder sleeve are extensively avoided due to the nearly identical thermal expansion characteristics of the sealing ring and the cylinder sleeve, none the less considerable thermal stresses occur in the light metal cylinder head and can cause heat cracks and destruction of the cylinder head.
It is an object of the present invention to improve a cylinder of the aforementioned general type in a simple manner in such a way that thermal stresses in the light metal cylinder head are reduced.
It is a further object of the present invention that the sealing surfaces have a strength as high as possible.